Meanwhile, stock for Moderna, which is based in the eastern state of Massachusetts, gained more than 24% to $82.93 a share after the company announced its Phase 1 trial of a possible coronavirus vaccine showed positive results to prevent new infections.

The company’s initial test embraced just eight patients, but Moderna said it is launching a large clinical trial in July to determine whether the vaccine works.

Moderna is one of several U.S. biotech companies searching for a coronavirus vaccine, with a huge financial bonanza at stake for whichever company is the first to widely market a successful product.

President Donald Trump said a vaccine could be available by the end of 2020, but some health experts have expressed skepticism about his timetable as unlikely.

Trump has pushed states across the country to reopen for commerce, even as the country’s world-leading coronavirus death toll nears 90,000 and is projected to hit 147,000 by early August.

Moderna said it traced the results in the eight patients for a month and a half, giving them small and medium doses of the test vaccine which showed it gave them virus-fighting antibodies at or above those for patients who have recovered from COVID-19. The favorable results do not prove the vaccine works but suggest that it would give patients a degree of immunity.

“The Moderna team continues to focus on moving as fast as safely possible to start our pivotal Phase 3 study in July, and if successful, file a (biologics license application),” Moderna chief executive Stephane Bancel said. “We are investing to scale up manufacturing so we can maximize the number of doses we can produce to help protect as many people as we can from SARS-CoV-2.”

Moderna’s announcement came just days after one of its directors, Moncef Slaoui, announced he was leaving the company to become chief scientist for Operation Warp Speed, a Trump effort to speed up vaccine development.

Critics cited what they contended was Slaoui’s apparent conflict of interest, ownership of Moderna stock options worth $10 million. Moderna has received $483 million from a U.S. government agency, the Biomedical Advanced Research and Development Authority.

“Slaoui’s blatant financial conflicts of interest disqualify him for the role of vaccine czar, unless he commits immediately to global vaccine access conditions over the obvious profit interests of the corporation he serves,” said Peter Maybarduk, director of the Access to Medicines Program at Public Citizen, a consumer advocacy group.

Democratic Sen. Elizabeth Warren of Massachusetts, a frequent Trump critic, said Slaoui should divest his stock options, tweeting that it is “a huge conflict of interest for the White House’s new vaccine czar to own $10 million of stock in a company receiving government funding to develop a COVID-19 vaccine.”